Refrigerating apparatus



July 30, 1946. .A. A. MccoRMAcK 2,405,042

REFRI GERAT ING APPARATUS Filed Sept. 27, 1945 Patented July 30, 1946 REFRIGERATING APPARATUS Alex A. McCormack, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application September 27, 1943, Serial No. 503,949

6 Claims.

This invention relates to refrigerating apparatus and more particularly to an improved compressor and unloading arrangement.

One object of this invention is to provide a centrifugally operated unloader valve which also serves to open a passage from the inlet to the outlet of the compressor in the event that the compressor is started up in the wrong direction.

It frequently happens that when a polyphase compressor motor is first plugged in to a polytion.

the compressor.

through the unloader valve.

In the drawing:

motor compressor unit;

its open position.

vanes 2 2.

frigerant together with any entrained lubricant is discharged directly into the casing It] through the outlet 30 in accordance with well known practice. It will be noted that the compressor [4 is mounted on a plurality of blocks 32 which are welded or otherwise secured to the bottom wall A passage 48 has been The lower portion 55 of the casing The lubricant level fluctuates during opera- A certain amount of lubri- The upper end of the elephase system the phase connections will be wrong of the casing it. A plurality f bolts 34 only one in which case the motor will operate in the wrong of which shows up in Fig. 1 holds the compressor direction. Since there is no convenient way of in assembled relationship with respect to the quickly determining the correct phase connecblocks 32. tions, it is important to provide some means to 5 The motor i2 is a polyphase motor which inunload the compressor during full speed operacludes the usual motor stator 40 and a rotor 42. tion of the compressor in the event that the com The rotor s2 is secured directly to the main compressor motor starts rotating in the wrong direcpressor shaft 18 as shown. The shaft i8 is provided with a center bore 44 which communicates Another object of this inventio is o p v e with a radial bore 46 as shown. A circumferena centrifugally operated unloader valve which is tial groove 19 is provided in the shaft directly in spring biased to the closed position and in which line with radial bore 4%. the centrifugal means is normally ou Of Contact provided in the compressor frame as shown and with the main valve parts during operation of serves to connect the inlet of the compressor with 5 the bore 44.

A furt O j o this invention s to provide it! serves as a lubricant reservoir in which the an inexpensive unloader valve which does not relubricant is subjected to a pressure correspondquire special pipes for conveying the refrigerant ing to the pressure at the outlet of the compressor.

Further objects and advantages of the present tion but at no time uncovers the lower end of the invention will b pp r n fr m h fo lowin shaft is. Inasmuch as the lubricant is subjected d e p reference being h d 130 the eeeemto a high pressure, a certain amount of it will find Dany drawing, W e ein a preferred form of the its way up along the shaft l8 into the main compresent invention is clearly shown. pression chamber.

cant will also be carried along with the refriger- Fig. 1 shows somewhat diagramm lly my ant and is added to the lubricant which leaks into improved unloader valve mounted on a i-vane the compression chamber along the shaft l8 and will serve to help lubricate the upper portion of 2 is a p V w O the d r valve W the compressor shaft. Inasmuch as the pressure parts broken away so as to more clearly show prevailing within the passage 48 and the circumthe arrangement of the parts; and ferential shaft groove 49 corresponds to the suc- Fig. 3 is a sectional view showing the valve in tion pressure, there will be a definite tendency for some of the lubricant to flow upwardly along Referring HOW to the drawing, reference nuthe upper shaft bearing and to return to the inmeral 0 designates a substantially cupp d let of the compressor through the passage 48. motor-compressor casing within which a motor T upper end of the central bore 44 i enl2 and a Comp e N are disposed as s W larged so as to receive a valve seat element 52 The upper end of the casing li is closed by means which is provided with a circumferential recess of a cap member l6 which is welded or otherwise within which a neoprene basket 54 has been vulsecured to the cup-shaped casing 10. 50 canized prior to the insertion of the element 52 For purposes of illustration a l-vane type of .into the shaft bore. ported rotary compressor has been shown which ment 52 is provided. with a neoprene valve seat includes the usual drive shaft l8, rotor 20 and ring 56 which is vulcanized to the element 52 at The refrigerant to be compressed the same time that the neoprene gasket 54 is enters the compressor through the inlet passage 55 vulcanized within the circumferential groove provided in the member 52. While I refer to the use of neoprene for the valve seat 56 and the gasket 56, it is obvious that any other rubberlike material which is uneffected by the particular refrigerant and lubricant used may be employed without departing from the spirit of this invention. The term rubber-like as used herein is intended to include natural rubber, synthetic rubbers or the equivalent.

A valve plate 58 which constitutes a part of a centrifugal unloading means is adapted to be moved into and out of engagement with the ring 56 so as to open and close the upper end of the passage M. With this type of valve seat and valve plate the problem of alignment of parts is simplified. The centrifugal unloading mechanism includes a stamped inverted U-shaped frame 6d, the legs of which are secured to the upper end of the motor rotor 42 by means of the screws 52 as shown in Fig. 2. A pin 64 is journaled in the side arms of the U-shaped frame if; as shown and supports a valve operating element 56. The one end of the member 66 carries a weight 88 and the other end of the member 66 is provided with a pair of upstanding lugs 753 which are adapted to engage the bottom side of the valve plate 53 so as to unseat the valve when the compressor comes to a stop or is operating at slow speeds. A spring '52 biases the valve plate 53 into valve closing position. spring M tends to push the weighted end of the member 6% downwardly and is strong enough to overcome the force of the spring i2 when the centrifugal efiect of the weight 68 drops below a predetermined value. Weight 63 with respect to the pivot point of the element 66 is such that the rotation of the motor tends to cause weight 58 to fly outwardly from the central axis of the shaft 58 and upwardly.

When the motor is operating at normal operating speeds the valve is held closed solely by the spring 72 and the pressure difference existing on opposite sides of the valve plate 58 and the upstanding lugs 16 move downwardly far enough so as to be out of engagement with the valve plate This being the case the centrifugal force does not interfere with opening of the valve in case the motor is started up in the wrong direction in which case the pressure within the passage 32 would very quickly exceed the pressure prevailing in the casing lfl. It will be noted that the connection between the valve plate 513 and the centrifugal means constitutes a form of lost motion connection and that the centrifugal force does not force the valve plate 58 to move in either direction but 'merely overcomes the force of the spring M which at all times tend to hold the valve open. This is an important feature in a refrigerating system or any other compression system using a check valve in the suction line and using a polyphase motor for driving a rotary compressor.

Under normal operating conditions the gas or refrigerant to be compressed enters the compressor through the inlet line 24 and leaves the casing it through the outlet line 8&3. When used in a refrigerating system the outlet 86 would be connected to a condenser wherein the refrigerant would be condensed before being discharged through a conventional pressure reducing means into an evaporator wherein the refrigerant would be converted into vapor before returning to the suction inlet 24.

While the form of embodiment of the invention as herein disclosed constitutes a preferred The arrangement of the form, it is to be understood that other forms might be adopted, as may come Within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerating system having a high pressure portion in which refrigerant is main tained at condensing pressure and a low pressure portion in which the refrigerant is maintained at evaporating pressure, a rotary compressor for withdrawing refrigerant from the low pressure portion and for discharging the refrigerant at a higher pressure into said high pressure portion, a compressor operating shaft, a refrigerant passage on said shaft connecting the high pressure portion and the low pressure portion, a pressure operated valve carried by said shaft controlling the flow through said shaft passage, and centrifugal means exerting an opening force on said valve, said centrifugal means including a lost motion connection whereby the valve is free to move to the open position in response to pressure changes without hindrance from said centrifugal means.

2. Compression apparatu comprising a casing, a compressor within said casing, a compressor operating shaft having a compressor unloading passage provided therein, a valve assembly mounted on said shaft having a Valve port communicated with said passage, first spring means biasing said valve to closed position, second spring means for holding said valve in the open position against the force of said first spring when said shaft is operating at a speed below a predetermined value, and speed responsive means for overcoming the holding effect of said second spring at speeds above said predetermined value.

3. In a compression system, a ported rotary compressor having an inlet and an outlet, a polyphase motor for driving said compressor, a

.,= check valve arranged in said inlet, means providing a passage from the inlet of said compressor to the outlet of said compressor, a relief valve in said passage, spring means for holding said relief valve in open position, means responsive to rotation of said compressor for overcoming the force of said spring means, and means for urging said valve towards closed position when said last named means overcomes said spring means.

4. In combination with a rotary compressor having a rotary drive shaft provided with an unloading passage communicating with the inlet of the compressor, an unloader valve carried by said drive shaft for controlling the flow through said passage comprising means forming a valve seat on the upper end of said shaft, a valve element cooperating with said valve seat, a spring holding said valve element against said seat, bracket means secured to said shaft for holding said spring in place, speed responsive means including a lever pivoted on said bracket means arranged for exerting a force on said valve element in the valve opening direction at reduced compressor speeds and arranged out of effective contact with said valve element at normal operating speed of said shaft whereby said valve element is free to move to open position in response to an abnormally high pressure in said passage.

5. In combination with a rotary compressor of the type in which the direction of flow of gas through the compressor is determined by the direction of rotation of the compressor, a compressor operating shaft, a casing into which said compressor discharges, means forming an inlet passage for said compressor, a check valve in said inlet passage, and means for unloading said compressor in response to either a reduction in the speed of said compressor or operation of the compressor in the wrong direction, said last named means comprising an unloader passage in said shaft, a check valve controlling the flow of fluid through said passage, spring means normally preventing opening of said second named check valve when said compressor is operating in the one direction at normal speeds of rotai tion, and centrifugal means for overcoming said spring means at slow speeds of said compressor so as to unload said compressor at said slow speeds, said centrifugal mean being so constructed and arranged as to never exert a valve closing force.

6. In a rotary compressor for withdrawing gas from a low pressure zone and for discharging the gas at a higher pressure into a high pressure zone, a compressor operating shaft, a gas passage in said shaft connecting the high pressure zone and the low pressure zone, a pressure-operated valve carried by said shaft controlling the flow through said shaft passage, and speed responsive means exerting an opening force on said valve, said speed responsive means including a lost motion connection whereby the Valve is free to move to the open position in response to pressure changes without hindrance from said speed responsive means.

ALEX A. MCCORMACK. 

